Capacitive sense arrays may be used to replace mechanical buttons, knobs and other similar mechanical user interface controls. The use of a capacitive sense element allows for the elimination of complicated mechanical switches and buttons, providing reliable operation under harsh conditions. In addition, capacitive sense elements are widely used in modern customer applications, providing new user interface options in existing products. Capacitive sense elements can be arranged in the form of a capacitive sense array for a touch-sensing surface. When a conductive object, such as a finger, comes in contact or close proximity with the touch-sensing surface, the capacitance of one or more capacitive touch sense elements changes. The capacitance changes of the capacitive touch sense elements can be measured by an electrical circuit. The electrical circuit converts the measured capacitances of the capacitive sense elements into digital values.
Transparent touch screens that utilize capacitive sense arrays are ubiquitous in today's industrial and consumer markets. They can be found on cellular phones, GPS devices, cameras, computer screens, MP3 players, digital tablets, and the like. In contemporary cellular phones and smart phones, touch screen area is of significant concern to manufacturers given the small amount of space available for user interaction. As such, manufacturers seek a touch screen that maximizes its useable area while maintaining uniform position tracking accuracy. However, conventional designs exhibit considerable position tracking error near the edges of the touch screen. New technologies are sought to help improve edge performance in mutual capacitance arrays.